Drill bit for downhole electrocrushing drilling

Abstract

An electrocrushing drill bit comprises a bit body and at least one electrode coupled to a power source and the bit body, wherein the at least one electrode having a distal portion for engaging with a surface of a wellbore. The electrocrushing drill bit comprises a ground structure coupled to the bit body proximate to the at least one electrode and having a distal portion for engaging with the surface of the wellbore, wherein the ground structure comprises a transverse ground structure.

What is claimed is: 
     
       1. An electrocrushing drill bit, comprising:
 a bit body; 
 at least one electrode coupled to a power source and the bit body, the at least one electrode having a distal portion for engaging with a surface of a wellbore, wherein the at least one electrode further comprises a slot in a face of the at least one electrode; and 
 a ground structure coupled to the bit body proximate to the at least one electrode and having a distal portion for engaging with the surface of the wellbore, wherein the ground structure comprises a transverse ground structure. 
 
     
     
       2. The electrocrushing drill bit of  claim 1 , further comprising:
 an insulator coupled to the bit body between the at least one electrode and the ground structure. 
 
     
     
       3. The electrocrushing drill bit of  claim 1 , wherein the ground structure comprises an outer ground ring. 
     
     
       4. The electrocrushing drill bit of  claim 3 , wherein at least one of the outer ground ring and the transverse ground structure comprises at least one fluid flow port. 
     
     
       5. The electrocrushing drill bit of  claim 1 , wherein the transverse ground structure comprises at least three segments. 
     
     
       6. The electrocrushing drill bit of  claim 5 , wherein the at least one electrode comprises at least one electrode positioned between two segments of the at least three segments. 
     
     
       7. The electrocrushing drill bit of  claim 6 , wherein a voltage is applied at a different repetition rate to the at least one electrode positioned between two segments in comparison to other electrodes positioned between other segments. 
     
     
       8. The electrocrushing drill bit of  claim 6 , wherein a voltage applied to the at least one electrode positioned between two segments is at a different level in comparison to a voltage to other electrodes positioned between other segments. 
     
     
       9. The electrocrushing drill bit of  claim 6 , wherein each of the at least one electrode positioned between two segments comprises a wedged-shape electrode. 
     
     
       10. The electrocrushing drill bit of  claim 6 , wherein each of the at least one electrode positioned between two segments comprises an elliptical-shape electrode. 
     
     
       11. The electrocrushing drill bit of  claim 6 , wherein the at least one electrode comprises multiple groups of electrodes such that each group of the multiple groups of the electrodes is positioned between two segments of the at least three segments. 
     
     
       12. The electrocrushing drill bit of  claim 11 , wherein a voltage is applied at a different repetition rate to at least one group of the multiple groups of the electrodes in comparison to others of the multiple electrodes. 
     
     
       13. The electrocrushing drill bit of  claim 11 , wherein a voltage applied to at least one group of the multiple groups of the electrodes is at a different level in comparison to a voltage to others of the multiple electrodes. 
     
     
       14. The electrocrushing drill bit of  claim 1 , wherein the at least one electrode and the ground structure is positioned in relation to each other such that an electric field produced by a voltage applied between the ground structure and the at least one electrode is increased at a portion of the at least one electrode proximate to the distal portion of the electrode and at a portion of the ground structure proximate to the distal portion of the ground ring. 
     
     
       15. A downhole drilling system comprising:
 a drill string; 
 a power source; and 
 a drill bit coupled to the drill string and the power source, the drill bit comprising, a bit body;
 at least one electrode coupled to the power source and the bit body, the at least one electrode having a distal portion for engaging with a surface of a wellbore, wherein the at least one electrode further comprises a slot in a face of the at least one electrode; and 
 a ground structure coupled to the bit body proximate to the at least one electrode and having a distal portion for engaging with the surface of the wellbore, wherein the ground structure comprises a transverse ground structure. 
 
 
     
     
       16. The downhole drilling system of  claim 15 , further comprising:
 an insulator coupled to the bit body between the at least one electrode and the ground structure. 
 
     
     
       17. The downhole drilling system of  claim 15 , wherein the ground structure comprises an outer ground ring. 
     
     
       18. The downhole drilling system of  claim 17 , wherein at least one of the outer ground ring and the transverse ground structure comprises at least one fluid flow port. 
     
     
       19. The downhole drilling system of  claim 15 , wherein the transverse ground structure comprises at least three segments. 
     
     
       20. The downhole drilling system of  claim 19 , wherein the at least one electrode comprises at least one electrode positioned between two segments of the at least three segments. 
     
     
       21. The downhole drilling system of  claim 20 , wherein a voltage is applied at a different repetition rate to the at least one electrode positioned between two segments in comparison to other electrodes positioned between other segments. 
     
     
       22. The downhole drilling system of  claim 21 , wherein a voltage applied to the at least one electrode positioned between two segments is at a different level in comparison to a voltage to other electrodes positioned between other segments. 
     
     
       23. The downhole drilling system of  claim 21 , wherein each of the at least one electrode positioned between two segments comprises a wedged-shape electrode. 
     
     
       24. The downhole drilling system of  claim 21 , wherein each of the at least one electrode positioned between two segments comprises an elliptical-shape electrode. 
     
     
       25. The downhole drilling system of  claim 21 , wherein the at least one electrode comprises multiple groups of electrodes such that each group of the multiple groups of the electrodes is positioned between two segments of the at least three segments. 
     
     
       26. The downhole drilling system of  claim 25 , wherein a voltage is applied at a different repetition rate to at least one group of the multiple groups of the electrodes in comparison to others of the multiple electrodes. 
     
     
       27. The downhole drilling system of  claim 25 , wherein a voltage applied to at least one group of the multiple groups of the electrodes is at a different level in comparison to a voltage to others of the multiple electrodes. 
     
     
       28. A method comprising:
 deploying a drill bit downhole in a wellbore, the drill bit comprising,
 a bit body; 
 at least one electrode coupled to a power source and the bit body, the at least one electrode having a distal portion for engaging with a surface of the wellbore, wherein the at least one electrode further comprises a slot in a face of the at least one electrode; and 
 a ground structure coupled to the bit body proximate to the at least one electrode and having a distal portion for engaging with the surface of the wellbore, wherein the ground structure comprises a transverse ground structure; 
 
 supplying an electrical energy to the drill bit; 
 supplying an electrocrushing drilling fluid to the drill bit; 
 forming an electrical arc between the portion of the at least one electrode proximate to the distal portion of the at least one electrode and the portion of the ground structure proximate to the distal portion of the ground structure of the drill bit; 
 fracturing a rock formation at an end of the wellbore with the electrical arc; and 
 removing fractured rock from the end of the wellbore with the electrocrushing drilling fluid. 
 
     
     
       29. The method of  claim 28 , wherein the drill bit comprises an insulator coupled to the bit body between the at least one electrode and the ground structure. 
     
     
       30. The method of  claim 28 , wherein the ground structure comprises an outer ground ring. 
     
     
       31. The method of  claim 30 , wherein at least one of the outer ground ring and the transverse ground structure comprises at least one fluid flow port. 
     
     
       32. The method of  claim 30 , wherein the transverse ground structure comprises at least three segments. 
     
     
       33. The method of  claim 32 , wherein the at least one electrode comprises at least one electrode positioned between two segments of the at least three segments. 
     
     
       34. The method of  claim 33 , wherein a voltage is applied at a different repetition rate to the at least one electrode positioned between two segments in comparison to other electrodes positioned between other segments. 
     
     
       35. The method of  claim 33 , wherein a voltage applied to the at least one electrode positioned between two segments is at a different level in comparison to a voltage to other electrodes positioned between other segments. 
     
     
       36. The method of  claim 33 , wherein each of the at least one electrode positioned between two segments comprises a wedged-shape electrode. 
     
     
       37. The method of  claim 33 , wherein each of the at least one electrode positioned between two segments comprises an elliptical-shape electrode. 
     
     
       38. The method of  claim 33 , wherein the at least one electrode comprises multiple groups of electrodes such that each group of the multiple groups of the electrodes is positioned between two segments of the at least three segments. 
     
     
       39. The method of  claim 38 , wherein a voltage is applied at a different repetition rate to at least one group of the multiple groups of the electrodes in comparison to others of the multiple electrodes. 
     
     
       40. The method of  claim 38 , wherein a voltage applied to at least one group of the multiple groups of the electrodes is at a different level in comparison to a voltage to others of the multiple electrodes. 
     
     
       41. The method of  claim 28 , wherein the at least one electrode and the ground structure positioned in relation to each other such that an electric field produced by a voltage applied between the ground structure and the at least one electrode is increased at a portion of the at least one electrode proximate to the distal portion of the electrode and at a portion of the ground structure proximate to the distal portion of the ground ring.